robert clarke
New member
Maybe that the cap on the fuel tank is not venting (letting air into the tank as the fuel is used). I had the same problem years ago with a gas engine swather. Would run perfectly for 15 or 20 minutes and then start to run poorly and then stop. Finally I thought I better check the gas tank and make sure there was still gas in it - even though I had only filled a few hours earlier. When I turned the cap loose on the top of the tank there was a bonk, as the sides of the tank sprunge outward to their original positions. A vaccum in the tank. The engine started right up and ran the way it should all day. Left the cap in half lock position that day, so it would vent. Got a new cap and no more trouble. When the vaccum in the tank gets high enough, the fuel pump cannot suck the fuel anymore and the engine runs out of fuel.